T6-A/T6 Compact Horn Subwoofer
The T6 has been around for some time now, it is a great way to fix the bass as long as you do not require earthquake levels, and the T6-A provides both dsp processing and amplification for both the subwoofer and the main speaker.
The product presentation is now updated with more technical information, showing all relevant performance data:
https://www.kvalsvoll.com/Services/T6_en.htm
Specifications:
https://www.kvalsvoll.com/Services/T6_en.htm#2
Not so sure if this new additional data is of any use for the typical potential customer, but anyway, it is there now.
T6 Acoustic loading and port contribution
Port output and driver output can not be measured practically because each individual contribution can not be isolated, any measurement will also have a significant contribution from the other output. But the simulation can show each output, and then we see that the port output from the small horn contributes across a wide frequency range, with significant output from the port up to around 100Hz.
This is different from a typical ported enclosure, where the port output has a smaller bandwidth.
T6 is tuned so the port output increases towards lower frequencies, which gives the desired slightly downwards sloping frequency response, and reduces driver cone movement more at the lowest frequencies where it matters most.
Output from the port is delayed relative to the driver cone output, and this can be observed in the group delay chart:
In compact horn systems the GD is fairly flat across a wide part of the frequency range, it does not destroy transient response, it is just a delay of the signal. At very low frequencies the delay increases, due to the roll-off.
I wanted to show this, in an attempt to explain the differences between this very small Compact Horn design and a typical ported box. The acoustic loading is different, loading works across a wide frequency range, and loading is very efficient.
T6 port and driver output - trying to measure directly
This is how it looks like when trying to measure this near-field, we see the sum matches the simulation well, but the driver and port output does not show an accurate presentation of the actual signals:
The reason for this measurement error is that when measuring driver cone output the port output is also present at this location, adding to the measured signal. Likewise, when measuring port output, even with the mic inside the port, the driver cone output is still present here as well, so the mic does not capture only port output, it gets all sound that is present at that location.
T6 with small Revel speakers in a typical living room setup:
Test by Erin, of some small subwoofers:
https://www.youtube.com/watch?v=g2PCemcuRZE&t=675s
Real numbers sometimes are merciless. Their marketing tells a story about "14Hz", reality shows a very different situation. The small KEF, applauded by the "hifi-press", has around 10dB less output capacity at 30Hz, compared to the T6. That is a very significant and definitely noticeable difference.
The numbers presented by Erin in the video shows that the only thing those subwoofers have in common with the T6, is that they are all small size.